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POST
Python

Authorizations

X-Auth-Token
string
header
required

Project API key for sending traces and accessing project-scoped resources. Format: sk-lw-... (no underscore). Obtain one by creating a project via the Admin API or the LangWatch UI.

Query Parameters

projectId
string
required

The project the file is stored for.

Body

multipart/form-data
file
file
required

The file to store.

datasetId
string

The dataset that owns the file. Omit it while the dataset is still a draft.

Response

The reference the cell holds, and the file's metadata.

url
string
required

The value to write into the cell, and the address the file is served from.

name
string
required

The file name the reference carries.

mediaType
string
required

The media type the file is stored under.

sizeBytes
number
required

The size of the stored file, in bytes.

Last modified on September 22, 2026